The last two times I have pulled a trailer (medium size bass boat) and the temperature was hot (90-94) my 2002 F-150 with a 4.6 ran fine for a while. After building up some temperature and running without overdrive the speed would begin to decrease. Any attempt to increase the speed seemed to make the problem worse and the rpms would increase like the transmission was the problem. When I would pull off and wait a couple of minutes the problem would seem to cure itself for about 5 minutes and then start again. A local mechanic seemed to think the problem was the fuel pump (which is part of a module). Anyone else got any ideas before I spend the $400 dollars for a fuel pump and hope that was really the problem. Thanks for anyone's help--

 

So...let me get this right...You start to slow down, so you step on it, and the motor just revs up, and you don't go faster correct?? Do you slow down or does your speed remain constant when this happens?

 

The rpm's increase but the speed continues to drop. If I baby the accelerator I can get the speed to constant if the terrain is level. If I approach a hill the speed will continue to drop. The rpms will only increase if I really get on the accelerator (to drop to a lower gear) but the speed will continue to decrease. The mechanic said the engine is starving for fuel and is trying to compensate by increasing the rpms. He said it was about the same as a clogged fuel filter which I changed 2 weeks ago to try the cheap way to solve the problem. Mileage is 56,000. Any advise?

 

Sounds more transmission related to me. It seems as if it is slipping. Check the level of the fluid.

 

I'm no mechanic. There are many here who know much more than I about these vehicles. I do know not to throw parts at these problems. Especially $400 dollar parts.

I assume there is no CEL (check engine light). No flashing of the OD(overdrive) light. Have the codes read from the PCM. Autozone will do it free of charge. Thre may be codes in memory which will not result in a CEL. Then have the tranny codes read. You'll probably have to pay for this. Go to a "chain" transmission shop with the equipment to read the codes as part of a "diagnostic" (which should also include a road test). Get the actual trouble codes and post them here. I'm sure someone will be able to help.

Bill

 

You have a tranny issue. Engine continues to rev but speed falls, yeppers tranny all the way. Save the 400 and go to a tranny shop they will test drive it for free.... good luck...sucks to be you today

 

Thanks for the info.

 

Thanks, I will have to try that. Only problem is it will not happen unless I am pulling a trailer and the air temperature is 90 or more.

 

Start with the basics. Check the fluid. Is it burnt? Is it nice and pink? Is it up to the fill line? Make sure when you check the tranny fluid leve, that the truck is running, and the transmission is in PARK. If there is enough fluid and it's fresh, then take the truck to a tranny shop and tell them what is happening. If they can't figure it out, then take them on a drive when it is hot out, with the trailer.

 

Thanks for all the help. I will let you know what I find out. Glad there is a place I can get some "unbiased" assistance.

 

Just remember, we're not professionals, we just act like it These are all random guesses as to what it could be, but they ARE a good starting point.